The objective of the proposed research is to provide rationale for the proposed hypothesis that viral cancerogenesis is due to the incorporation of viral initiation sites into the host DNA. Viral initiation sites should be resistant to host control systems, the unsuppressed initiation should lead to uncontrollable replication of host DNA and ultimate to neoplasia. Experiments will be performed on the model of T4 bacteriophase, to determine: the model and mechanism of multiple initiations, preferential and possibly sequential initiation of specific sites in DNA replications; to explore the possibility of inhibition by host anti-initiators of some of these initiative areas; to prove or disprove the possibility that circular permutations are abolished prior to the initiation of DNA replicatio, and finally to the further explore the role of the RNA-DNA co-polymer in the initiation of DNA replication and its possible role in the continuation of DNA synthesis. The major techniques used during this research will be: ultracentrifugation, utilizing both sedimentation velocity and equilibrium gradients; double and triple labeling with isotopes, and electronmiscroscopy of replicative DNA. These approaches will be combined with annealing against nitrocellulose filters charged with separated strands, and with enzymatic assays, mainly utilizing enzymes specific for 3' or 5' ends of single-stranded DNA.